Discharger for centrifugal separators



' Get. 18, 1949. E,

DISCHARGER FOR CENTRIFUGAL SEPARATORS 3 Shee'ts-Sheet 1 Filed Oct. 16,1945 Oct. 18, THOLL DISCHARGER FOR CENTRIFUGAL SEPARATORS 3 Sheets-Sheet2 Filed Oct. 16, 1945 Oct. 18, 1949. J. E. THOLL I DISCHARGER FORCENTRIFUGAL SEPARATORS 3 Sheets-Sheet 3 Filed Oct. 16, 1945 PatentedOct. 18, 1949 DISCHARGER FOR CENTRIFUGAL SEPARATORS John E. Tholl,Needham, Mass., assignor to American Tool & Machine 00., Boston, Mass, acorporation of Massachusetts Application October 16, 1945, Serial No.622,573 3 Claims. (Cl. 210-70) This invention relates to centrifugalseparators, and is more especially concerned with the unloading ordischarging mechanism for machines of this type.

As is well understood by those skilled in this art, a considerablepercentage of the centrifugal separators such, for example, as thoseused in the sugar refining industry, are equipped with a scraper, plowor shoe so mounted that, after the conclusion of the separating action,the scraper can be moved down into the basket and its edge can be forcedinto the accumulation of solids on the basket wall in such a mannerthat, while the basket is rotated slowly, the solid material will bedislodged and will drop through the bottom of the basket.

The operation of such a scraper involves movement in two directions, oneoutwardly or toward the wall of the basket, and the other a traversingmovement parallel to said wall, and the operator must produce these twomovements simultaneously. For this purpose a gear mechanism customarilyis employed to create the traversing motion, but the movements of thescraper toward and from the basket wall are produced by operating a handlever. This involves considerable strength and skill, particularly ifthe consistency of the solids varies, so that some spots are much harderthan others, thus creating a tendency for the scraper to dig too deeplyat certain points and to bounce away from the load of solids at otherareas.

The present invention is especially concerned with the problem presentedby the foregoing considerations, and it aims to devise a mechanism bymeans of which the movements of the scraper can be produced with muchless effort and controlled far more accurately.

The nature of the invention will be readily understood from thefollowing description when read in connection with the accompanyingdrawings, and the novel features will be particularly pointed out in theappended claims.

In the drawings,

- Fig. 1 is a side elevation of a centrifugal separator, with some partsbroken away, showing the machine equipped with a discharging apparatusembodying this invention;

Fig. 2 is an elevation of the operating mechanism for the discharger ona larger scale than in Fig. 1;

Fig. 3 is a sectional view taken approximately on the line 3-3, Fig. 2;

Fig. 4 is a plan view of the operating mechanism with some of the casingparts broken away;

2 Fig. 5 is a sectional view taken substantially on the line 55, Fig. 4;and

Fig. 6 is a horizontal, sectional View of the mounting for the wormshaft by means of which the discharger plow or scraper is controlled.

The machine shown in the drawings comprises a centrifugal basket 2suspended on a vertical shaft 3 which may be driven either at highspeeds by the motor 4-, or at a lower discharging speed by the motor 5.The basket is enclosed in the usual casing or curb 6, all of theforegoing parts being of a well. known construction.

The discharger comprises a scraper I secured to the lower end of anupright shaft 8 which is mounted for vertical sliding movement in abushing it], Figs. 3 and 5, the latter being supported in a bracket l2bolted to the top of the casing 5. At its upper end the bushing H1 isflangedas shown at HI in Fig. 5, and this flange rests on the top of theadjacent portion of the bracket 12. Thus the bushing is mounted torotate in the bracket and it carries a key or spline l3, Fig. 3,

running in a key-way in the shaft 8, which com-' pels the shaft torevolve with the bushing but permits vertical movement of the formerrelatively to the latter.

Axial traversing movement of the shaft 8 is produced by a pinion l4keyed to a horizontal shaft I5 which is supported in bearings in thebracket l2 and has a hand wheel I6 secured to it. This pinion mesheswith arcuate rack teeth i! cut in the side of theshaft 8, as bestshownin Figs. 3 and 4, the arrangement being similar to that shown in myearlier Patent No. 2,036,974. Secured to the upper end of the shaft 8 isa stop 18, the shank of which is threaded into the shaft so that it isadjustable relatively to the latter, and the head of this member is madelarger in diameter than the shaft so that when the latter is lowered,the head [8 will engage the top of the flange In and limit such loweringmovement.

The mechanism provided by this invention for adjusting the scrapertoward and from the basket Wall comprises a worm gear or sector 20,bolted to a collar 2|, which closely encircles the flange I'll of thebushing it! and is secured to said flange by a set screw 22, Fig. 5.Meshing with the teeth of this sector is a worm 23, Figs. 4 and 5,pinned to a shaft 24 which is supported in bearings formed in asupplemental bracket or housing 25 bolted to the main bracket l2. A handwheel 26 is secured to one end of this shaft. By revolving the shaft,the worm' 23 acts through the gear 20, the bushing l 0 and key 13, torock the shaft 8 around its axis, together with the scraper 1 which isse cured to it. In this manner the scraper may be positively moved intocontact with the solid material on the inner wall of the basket.

Encircling the end portion of the worm shaft 24 where it projects beyondthe housing 25, is a coiled spring 27 which is confined between a loosewasher 28 and the stop nuts 30; Thus, while this entire shaft is free toslide endwise through its bearings, it is normally urged forward by theSpring 21, and this movement is limited by the abutment of the front endof the worm23 against the inner end of the bearing 25, Fig. 4. But theshaft can be moved backwardly, against the pressure of the ring, untilthe rearward end of the worm strikes the bearing 25".

In using this apparatus to discharge the load in the basket after thecentrifuging operation has been stopped, the workman first operates thehand wheel Hi to lower the scraper l down into the basket and then, byrevolving the hand wheel 26, heswings the scraper outward intoengagement with the layerof. solids supported on the basket wall.Because the worm 23 and the sector which it engages form an irreversiblemechanism, the movement of the scraper just described is performedpositively. If, therefore, the. rotation. of: the-hand wheel 26 isstopped when the scraper has been adjusted to the desired position, itwill remain in that position while the operator traverses the scraper byop erating the other: handwheel l 6.

This is a great convenience from the standpoint of the workman becauseat the start of a traversing movement of the scraper, either up or down,he can set the scraper-to take the desired depth of cut and then leavethe hand wheel in its adjusted position while he operates the other handwheel to make the complete traverse. In other words, he can adjust hisdepth of cut at the beginning of each traversing stroke, but need pay noattention to it at other times, knowing that the scraper will remain inthat position.

Should the scraper strike some part of the load which tends to make itswing outward and dig into the solids too deeply, any such movement ofit is positively prevented by the engagement of the forward end of theworm with the bearing 25'. Cm the other hand, if the scraper strikes ahard area, such as a seam on the inner wall of the basket, which tendsto force the scraper inwardly toward the axis of the basket, suchmovement is yieldingly permitted if the force is sumciently strong toovercome the pressure of the spring 2'3. The sliding movement of theworm and shaft so created, and which is permitted by the small lostmotion which the worm is allowed to have in its housing, is backward,toward the hand wheel, and is limited by the engagement of the worm withthe bearing 25". It is purely a transient action, but the constructionproviding for it is valuable in preventing breakage of some of the partswhen the scraper meets a hard obstruction. The spring, of course,operates through its connections with the scraper to return the latterto its original position of adjustment as soon as it has passed theobstrucion.

Preferably the collar 2! is provided with two arms carrying stop screwsand 32 adjustable to engage parts a and b on the casing 25 and servingas stops to determine both the inner and outer limits of movement of thescraper. That is, the stop 32 can be set to limit positively the depthof cut, as above described where the bearing 25' does notstop thescraper at the desired point. In other words, the limits imposed on thesliding movement of the worm 23 by the stops 25' and 25 work withinextreme limits determined by the stop screws 3| and 32. It may beobserved that in Fig. 4 the scraper is shown in an abnormal position inorder to provide space for Fig. 5. Usually it is located at about anangle of 30, in a counter-clockwise direction away, from the positionthere shown. A removable cover 29 for the worm 23 is secured to thesupplemental bracket 25.

This invention provides an organization with which the entiredischarging operation can be performed more easily, rapidly andaccurately than with the prior art mechanisms of this character. Itshould be noted that the shafts on which the two hand wheels are securedare located, one slightly above the other, but at right angles to eachother, and that the hand wheels themselves are positioned closelyadjacent to each other where they can be operated conveniently andsimultaneously by a single workman. They are located at fixed levels andin substantially fixed positions suited to the convenience of theworkman and are unaffected by the changes in position of the scraper.For these reasons, and becauseof the nature of the mechanism, theunloading operation is made positive, without sacrificing safety of theparts, and is made easy for the workman while securing great accuracyand smoothness of operation.

While I have herein shown and described a preferred embodiment of myinvention, it will be evident that the invention may be embodied inother forms without departing from the spirit or scope thereof.

Having thus described my invention, what I desire to claim as new is:

1. In a centrifugal separator, the combination with a centrifugal basketsupported for rotation around a vertical axis, a curb in which it ismounted, a, discharger including a scraper, a vertical shaft on thelower end of which said scraper is secured and a rack and pinonmechanism operable to raise and lower said shaft; of a gear connectedwith said shaft to rotate therewith about the axis of the shaft, adriving worm meshing with said gear, a housing in which said worm ismounted, a second shaft on which said worm is fixed, bearings supportingsaid shaft with its worm for both rotative and axial sliding movement insaid housing, a hand wheel on said shaft for revolving it, said bearingslimiting said sliding movement, a spring loaded means on said shaftyieldingly holding it normally against one of said bearings, where itsconnection with said scraper prevent further movement of the lattertoward the inner wall of the basket except as such movement may beproduced by rotation of said worm, the worm when so positioned beingspaced from the other stop whereby a limited inward movement of saidscraper away from said wall is permitted against the tension of saidspring, and means on said curb supporting both said pinion and saidhousing in substantially fixed positions on the curb.

2. In a centrifugal separator according to preceding claim 1, aconstruction in which said shaft supporting the worm is mounted on ahorizontal axis, a horizontal shaft supporting the pinion of said rackand pinion mechanism, a hand wheel on the latter shaft, said means onthe curb for supporting said pinion and worm comprising a stationarybracket in which both said horizontal shafts are mounted, said handwheels being supported closely adjacent to each other at approximatelyright angles to each other and close to the edge of said curb wherebythey can be operated simultaneously by a single workman.

3. In a centrifugal separator, the combination with a centrifugal basketsupported for rotation around a vertical axis, a curb in which it ismounted, a discharger including a scraper, a vertical shaft on the lowerend of which said scraper is secured and a rack and pinion mechanismoperable to raise and lower said shaft; of a gear connected with saidshaft to rotate therewith about the axis of the shaft, said shaft havingadjustable stops connected thereto, a driving worm meshing with saidgear, a housing in which said worm is mounted, a second shaft on whichsaid worm is fixed, bearings supportingsaid shaft with its worm for bothrotative and axial sliding movement in said housing, a hand wheel onsaid shaft for revolving it, said bearings limiting said slidingmovement, a spring loaded means on said shaft yieldingly holding itnormally against one of said bearings where its connections with saidscraper prevent further movement of the latter toward the inner wall ofthe basket except as such movement may be produced by rotation of saidworm, the worm when so positioned being spaced from the other bear- 6ing whereby a limited inward movement of said scraper away from saidwall is permitted against the tension of said spring, said stops actingto limit the extreme inward and outward movement of the scraper, andmeans on said curb supporting both said pinion and said housing insubstantially fixed positions on the curb.

JOHN E. THOLL.

REFERENCES CITED The following references are of record in the file ofthis patent:

i UNITED STATES PATENTS Number Name Date 758,634 Fisher May 3, 19041,227,107 Blomfield May 22, 1917 1,474,331 Robertson et al Nov. 13, 19231,761,593 Sharples June 3, 1930 1,829,249 Beulitz Oct. 27, 19312,063,472 Tholl Dec. 8, 1936 FOREIGN PATENTS Number Country Date 40,790France May 17, 1932 (Addition to No. 660,770)

204,937 Great Britain Oct. 11, 1923 587,634 France Jan. 20, 1925

